1. Field of the Invention
The present invention relates to functional fluid compositions that contain selected compounds derived from alkylnaphthalenesulfonic acids. In particular, this invention relates to functional fluid compositions that contain selected salts and esters derived from mono-, di-, and/or poly-alkyl substituted naphthalenesulfonic acids. These sulfonic acid derivatives impart corrosion-inhibiting, rust-inhibiting, friction-modifying, oxidation-inhibiting, and antiwear properties to functional fluids.
2. Brief Description of Art
Various derivatives of alkylated benzenesulfonic and naphthalenesulfonic acid compositions have been used as corrosion inhibitors, rust inhibitors and wear control agents for a wide variety of functional fluids, including lubricants and hydraulic fluids. Such derivatives include neutral metal salts, basic metal salts, and amine salts derived from alkylated benzenesulfonic and naphthalenesulfonic acids.
These derivatives have been prepared by first alkylating benzene, naphthalene or alkylnaphthalene with a suitable alkylating agent in the presence of a catalyst. The most common alkylation method is the Friedel-Crafts method employing alkyl halides, alcohols or olefins. The Friedel-Crafts method for the alkylation of benzene and naphthalene with alkyl halides, alcohols, or olefins to produce the corresponding alkylated products has been extensively described in the literature and reviewed, e.g., by C. C. Price in xe2x80x9cOrganic Reactionsxe2x80x9d, Volume 3, Chapter 1, pages 1-82, John Wiley and Sons, Inc., 1946. The alkylation reaction, catalyzed by materials such as aluminum chloride, antimony pentachloride, ferric chloride, stannic chloride, zinc chloride, hydrogen fluoride, sulfuric acid, and phosphoric acid, must be carefully controlled to achieve the degree of alkylation required and to control the formation of poly-alkylation and rearrangement products (C. C. Price, supra). Rearrangement of the alkyl group can occur during the Friedel-Crafts alkylation reaction, so that one obtains a mixture of linear and branched alkyl-substituted aromatic compounds even when starting alkylating agents are linear. The position of substitution of the alkyl groups on the aromatic ring is dependent on the alkylating agent, reaction conditions, and type of catalyst utilized.
Another known method of alkylating benzene or naphthalene or alkylnaphthalenes to produce a composition substituted with linear alkyl groups is the two step synthesis that includes: (1) Friedel-Crafts acylation of benzene or naphthalene with an acyl halide, such as RCOCl (where R is a linear alkyl group), to form an acylated product, followed by (2) Clemmenson reduction or Wolff-Kirshner reduction of the carbonyl group. These reactions are well known in the literature and are discussed in textbooks, such as that by R. T. Morrison and R. N. Boyd entitled xe2x80x9cOrganic Chemistry,xe2x80x9d Third Edition, Chapters 12, 19, and 30, Allyn and Bacon, Inc., 1973.
The preferred commercial method of making polyalkylnaphthalenes has been the alkylation of naphthalene with propylene or butylene trimers or tetramers in the presence of a catalyst. This reaction is described in detail in U.S. Pat. No. 2,764,548 (King and Thielcke). The resulting alkylnaphthalenes have highly branched polypropylene or polybutylene chains (C9, C12 or C16 in length).
U.S. Pat. Nos. 5,401,896 and 6,071,864 teach the alkylation of naphthalene and alkylnaphthalenes with alkylation agents in the presence of zeolites. These patents do not teach or suggest making of the sulfonic acids or their derivatives from the resulting alkylnaphthalenes.
In the case of known commercial functional fluids that contain alkylated naphthalenesulfonic acid derivatives, the alkyl chains are derived from propylene or butylene trimers or tetramers. While such existing functional fluids are suitable for a wide variety of applications, it has now been discovered that if each of the alkyl chains in these derivatives is essentially linear while being at least 10 carbon atoms (C10) in length, significant improvements in corrosion inhibition, demulsibility, and wet filterability may be achieved. Two tests that are commonly used to assess wet filterability are the Wet AFNOR Filtration Test and the Wet Pall Test. The wet tests differ from the dry tests in that the wet tests contain a recommended amount of water. Accordingly, the present invention is based on these discoveries.
Therefore, one aspect of the present invention is directed to a functional fluid composition comprising a mixture of:
(a) at least one functional fluid base component; and
(b) an additive package comprising at least one derivative of a mono-, di-, or poly-alkylated naphthalenesulfonic acid selected from the group consisting of:
(i) neutral metal salts of said mono-, di-, and poly-alkylated naphthalenesulfonic acids;
(ii) basic metal salts of said mono-, di-, and poly-alkylated naphthalenesulfonic acids;
(iii) amine salts of said mono-, di-, and poly-alkylated naphthalenesulfonic acids; and
(iv) esters of said mono-, di-, and poly-alkylated naphthalenesulfonic acids;
wherein the mono-, di-, and poly-alkylated naphthalenesulfonic acids are represented by formula (I):
wherein R1, R2, R3 and R4 are individually selected from the group consisting of hydrogen or essentially linear hydrocarbyl groups having about 10 to about 14 carbon atoms; and wherein l, m, n and p are integers from 0 to 4 and the sum of l+m+n+p is at least 1; and wherein R1, R2, R3, or R4, is a hydrogen where either l, m, n or p is 0.
Another aspect of the present invention is directed to a hydraulic fluid which is dispersant-free and contains (a) at least one hydraulic fluid base component; and (b) an additive package as defined above.
A preferred aspect of the present invention is directed to a functional fluid composition comprising a mixture of:
(a) at least one functional fluid base component; and
(b) an additive package comprising at least one neutral or basic calcium salt of a mono-, di-, or poly-alkylated naphthalenesulfonic acid as defined above, preferably in an effective rust-inhibiting amount.
The incorporation of these particular alkylnaphthalenesulfonic acid derived compositions into the functional fluid formulations of the present invention provides several advantages over the commercially known functional fluids described above. Specifically, the functional fluids of the present invention have excellent rust- and corrosion-inhibiting properties and improved demulsibility, while maintaining the better hydrolytic stability, thermal stability, and antiwear performance of the functional fluids described above. In addition, these additives impart oxidation-inhibiting, friction-modifying, and antiwear properties to certain types of functional fluids. Specifically for hydraulic fluids, the present sulfonic acid derivatives have the advantages of providing a combination of good demulsibility, rust performance and the wet filterability performance, as assessed by the AFNOR and the Pall Tests. Passing this combination of tests is a common problem with the corresponding branched-chain type alkylarylsulfonic acid derivatives as well as with linear-chain type alkyl benzene sulfonic acid derivatives. Many suppliers of commercial hydraulic fluids add dispersants to hydraulic fluid formulations to overcome wet filtration problems. See U.S. Pat. No. 5,767,045, which provides an example of using this type of strategy. The present invention has the special advantage of not requiring the use of the additional dispersant to achieve good wet AFNOR performance for certain hydraulic fluid formulations.
Throughout this specification and claims, all parts and percentages are by weight, temperatures are in degrees Celsius, and pressures are at or near atmospheric unless otherwise clearly indicated.
As used in this specification and in the appended claims, the terms xe2x80x9chydrocarbylxe2x80x9d and xe2x80x9chydrocarbylenexe2x80x9d denote a group having a carbon atom directly attached to the naphthalene ring or amine and ester portion of the molecule and having a hydrocarbon or predominantly hydrocarbon character within the context of this invention. Such groups include the following:
(1) Hydrocarbon groups; that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl or cycloalkenyl), and the like, as well as cyclic groups wherein the ring is completed through another portion of the molecule (that is, any two indicated substituents may together form a ring). Such groups are known to those skilled in the art. Examples include methyl, ethyl, octyl, decyl, octadecyl, cyclohexyl, and the like.
(2) Substituted hydrocarbon groups; that is, groups containing non-hydrocarbon substituents which, in the context of this invention, do not alter the predominantly hydrocarbon character of the group. Those skilled in the art will be aware of the suitable substituents. Examples include halo, hydroxy, alkoxy, and the like.
(3) Pendent groups, that is, the groups such as alkoxy, carboxy and hydroxyalkyl.
(4) Hetero groups, that is, groups which, while predominantly hydrocarbon in character within the context of this invention, contain atoms other than carbon in a chain or ring otherwise composed of carbon atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, nitrogen and oxygen. Suitable hetero groups include, for example, amino, alkoxy, and carboxyl.
In general, no more that about three substituents or hetero atoms, and preferably no more than one, will be present for every 10 carbon atoms in the hydrocarbyl group.
Terms such as xe2x80x9calkylxe2x80x9d, xe2x80x9calkylenexe2x80x9d, and the like have meanings analogous to the above with respect to hydrocarbyl and hydrocarbylene.
The term xe2x80x9chydrocarbon-basedxe2x80x9d also has the same meaning and can be used interchangeably with the term hydrocarbyl when referring to molecular groups having a carbon atom attached directly to the polar group.
The term xe2x80x9cdispersant-freexe2x80x9d as used in the present specification and claims is defined to mean that no other compounds whose primary function is to disperse ordinarily oil-insoluble materials in the lubricant are added to the functional fluids of the present invention. Such materials are known to those skilled in the art.
The term xe2x80x9cpolyxe2x80x9d when referring to alkylated naphthalenesulfonic acid compounds in the present specification and claims is defined to mean that either three or four hydrocarbyl groups are attached to the naphthalene ring.
The term xe2x80x9cfunctional fluidsxe2x80x9d as used in the present specification and claims includes any and all functional fluid compositions that (1) are generally known in the art; and (2) contain an additive package that includes at least one derivative of a mono-, di-, or poly-alkylated naphthalenesulfonic acid as noted above. Suitable functional fluid applications include greases, lubricating oils, hydraulic fluids, metalworking fluids, and heat-transfer fluids.
The preferred functional fluids to which the present invention is directed include hydraulic fluids.
The term xe2x80x9chydraulic fluidxe2x80x9d as used in the present specification and claims includes any and all compositions that (1) are generally known in the art and (2) contain an additive package that includes at least one derivative of the mono-, di-, or poly-alkylated naphthalenesulfonic acid as noted above. These preferred hydraulic fluid compositions are useful in any system wherein a mechanical effort is converted to generate pressure at a first location, then the pressure is converted to a second mechanical effort at the second location. Thus, the hydraulic systems contemplated, where the present invention is useful include hydraulic brake systems, hydraulic steering mechanisms, hydraulic transmissions, hydraulic jacks and hydraulic lifts. Included among these are the hydraulic systems used in heavy equipment and transportation vehicles, including highway and construction equipment, railways, airplanes and aquatic vehicles. Also included are special or custom fluid-requiring systems, such as high pressure or temperature gradient systems, including those employed in arctic environments as well as those found in aerospace vehicles and the like.
The functional fluids of the present invention have two critical components. The first component is a base fluid [Component (a) noted above]. The base fluid component may be petroleum, synthetic, or biological in origin. Petroleum-derived base fluids (also sometimes called mineral oils) are the base fluids that are most often used in developing functional fluids. Synthetic base stocks, the second largest group in terms of use, are usually made from petroleum-derived organic chemicals. These synthetic base stocks are generally used for extremely demanding applications where petroleum-derived base fluids can not be used. Semi-synthetic base fluids are base stocks that are blended from synthetic base stocks and mineral oils. Such base stocks are used to benefit from the superior operating properties of the synthetic stocks, but at a lower cost. Base stocks of biological origin include vegetable oils and animal fats. These are often used to formulate environmentally compatible functional fluids. The present invention is useful in functional fluids that employ any of these types of base stocks. That is, the present invention is useful for all categories of base stocks, as defined by the American Petroleum Institute""s (API) Base Oil Classification System, viz. API Group I to Group V oils.
Besides the base fluid, functional fluids always contain additives. Additives improve the properties of functional fluids by either enhancing the desirable properties already present in the base fluids or by adding new properties to the base fluids. Commonly used additives include dispersants, detergents, friction modifiers, antiwear agents, extreme pressure agents, oxidation inhibitors, rust and corrosion inhibitors, emulsifiers, demulsifiers, pour point depressants, foam inhibitors, and viscosity modifiers.
For the present invention, at least one selected salt or ester derivative is present in the additive package as a rust-inhibitor, a corrosion-inhibitor, an oxidation inhibitor, a friction modifier, or an antiwear agent, depending on its structure. More particularly, these selected salt or ester derivatives are one or more of the derivatives of a mono-, di-, or poly-alkylated naphthalenesulfonic acid as noted above [Component (b)(i) to Component (b)(iv)]. These derivatives are made from mono-, di-, or poly-alkylated naphthalene that is converted into the corresponding sulfonic acid which is then transformed into the desired derivative. In terms of the use of the present invention, other classes of additives may or may not be present in this additive package.
The alkylated naphthalenesulfonic acid derivatives can have from 1 to 4 hydrocarbyl groups attached to the naphthalene ring, wherein the combined sum of the carbons in the 1 to 4 hydrocarbyl groups is at least 10 carbon atoms and preferably from 10 to 56. The naphthalene precursors to these derivatives are prepared by methods that form xe2x80x9cessentially linearxe2x80x9d hydrocarbyl chains. Suitable methods involve the alkylation of naphthalene with a C10 to C14 alpha olefin, a C10 to C14 primary alcohol, or a C10 to C14 primary alkyl halide (i.e. they contain a double bond, a hydroxyl group, or a halogen group at the end of a linear chain). Mixtures of C10, C12, and C14 homologues of these alkylating agents also can be used. These alkylation reactions are known to those skilled in the art and are generally conducted in the presence of a catalyst. Suitable catalysts include any of the Lewis acid or super acid catalysts known in the art. Suitable Lewis acids include aluminum chloride, boron trifluoride, iron trichloride, tin tetrachloride, zinc dichloride, and antimony pentafluoride. Acidic clays, silica, or alumina also are suitable. See for example U.S. Pat. Nos. 4,604,491 and 4,714,794. Suitable super acid catalysts include trifluoromethanesulfonic acid, hydrofluoric acid or trifluoromethylbenzenesulfonic acid. Other suitable catalysts include acidic zeolite catalysts, such as Zeolite Beta, Zeolite Y, ZSM-5, ZSM-35 and USY. In one embodiment of the present invention, it is preferred to alkylate naphthalene with an alpha olefin using aluminum chloride as the catalyst. The use of a co-catalyst such as nitromethane, nitrobenzene, or a low molecular weight alcohol to promote the reaction also is suitable. See, for example, U.S. Pat. No. 2,764,548 to King et al. In another embodiment, it is preferred to alkylate naphthalene with an alpha olefin using trifluoromethanesulfonic acid as the catalyst. It is important to note that the resulting alkylnaphthalene composition may contain varying amounts of dimer-, trimer-, or tetramer-alkylated naphthalene, which can result from polymerization of the olefin prior to alkylation.
In still another embodiment, compounds other than naphthalene may be alkylated to provide suitable alkylated naphthalenes. In particular, the addition of longer chain alkyl groups, e.g. about C10 to about C14, to short chain alkylated naphthalenes, (e.g. methyl-naphthalene, ethylnaphthalene, propylnaphthalene, butylnaphthalene) may be suitable.
Most preferred, the substrate of the present derivatives (b)(i) to (b)(iv) may be prepared by reacting naphthalene with an alpha olefin in the presence of aluminum chloride as a catalyst. The alpha olefin to naphthalene ratio may be between 1 to 4 moles of alpha olefin to each mole of naphthalene.
A critical feature of the present invention is that the hydrocarbyl chains on the naphthalene rings are all xe2x80x9cessentially linearxe2x80x9d. This means that branching is minimized or non-existent and the hydrocarbyl chains are predominantly linear. Hydrocarbyl chains prepared from C3 or C4 trimers or tetramers are explicitly excluded from this definition of xe2x80x9cessentially linear.xe2x80x9d The preferred essentially linear hydrocarbyl chains each are predominantly 10 to 28 carbon atoms in length and more preferably predominantly 12 or 24 carbon atoms in length (ie. C12.monomers or dimers). The present invention is a composition which can contain C10-14 monoalkyl-, C10-14 dialkyl-, C10-14 polyalkyl-naphthalene derivatives in various ratios.
The resulting alkylnaphthalene precursors can then be sulfonated by means known in the art. Sulfonation typically is conducted by reacting the alkylated naphthalene with a sulfonating agent, such as fuming sulfuric acid (oleum), sulfur trioxide, or chlorosulfonic acid. Examples of procedures for sulfonation are found in Jerry March, Advanced Organic Chemistry, Reactions, Mechanisms and Structure, 4th edition, John Wiley and Sons, p. 528, 1992. Typically, about 1 mole of sulfur trioxide is added preferably to each mole of alkylnaphthalene composition in a hydrocarbon solvent. The molecular weight of the alkylnaphthalene composition used for this reaction is the average molecular weight of all the alkylnaphthalene components present in the alkylate. Once the sulfonation reaction is complete, the sulfuric acid is removed and the hydrocarbon layer is washed with water to remove water-soluble byproducts.
The four classes of derivatives listed below can be prepared from the mono-, di-, and/or poly-alkylated naphthalenesulfonic acids using well known procedures.
The preferred neutral salts of the mono-, di-, and/or poly-alkylated naphthalenesulfonic acids are represented by formula (II): 
wherein R1, R2, R3, R4, l, m, n and p are the same as defined above; M is a metal selected from the group consisting of alkali metal, alkaline earth metal, transition metal, Group IVb metal and Group Vb metal; and x is the valence of the metal, M. When either l, m, n, or p is 0, then a hydrogen is the substituent on the ring structure as the respective R group.
If M is an alkali metal, it is preferred to use lithium, sodium, potassium, or mixtures thereof If M is an alkaline earth metal, it is preferred to use magnesium, calcium, strontium, barium, or mixtures thereof.
The term xe2x80x9ctransition metal or elementxe2x80x9d, as used in the present specification and claims, is defined as the metal in the periodic table that has partly filled d or f orbitals. Transition elements are listed in the middle of the long form of the Modem Periodic Table of Elements. Depending upon the supplier of the Periodic Table, transition elements are either listed as Group IIIa to Group VIIa, Group Ib, and Group IIb elements or Group 3 to Group 12 elements, or both. The version in Advanced Inorganic Chemistry by F. A. Cotton, Third Edition, John Wiley Publishers (1972) uses Roman numeral designations and the Learning Laboratories version (1996 copyright) uses Arabic numeral designations to list these elements. The preferred transition metals are zinc, copper, cerium, molybdenum, or mixtures thereof.
The term xe2x80x9cGroup IVb metalxe2x80x9d as used in the present specification and claims is defined as elements that contain 4 electrons in their valence shell. Again, depending upon the date of the Periodic Table, they are called either Group IVb elements or Group 14 elements, as described in the previous paragraph. The preferred metals belonging to this group are tin, lead, or mixtures thereof.
The term xe2x80x9cGroup Vb metalxe2x80x9d, as used in the present specification and claims, refers to elements that contain 5 electrons in their valence shell. The same as above, depending upon the date of the Periodic Table, they are either Group Vb elements or Group 15 elements, as described in the previous paragraph. The preferred metals belonging to this group are bismuth, antimony, or mixtures thereof In order to avoid confusion, Roman numeral group designations will be used in the rest of this patent document.
Besides these classes of neutral salts of mono-, di-, and/or poly-alkylated naphthalenesulfonic acids, it may be desirable in some instances to use mixtures of metals from these classes. For example, it may be desirable to use mixed metal sulfonates in some functional fluids. That is, the salts that are derived from the reaction of alkylnaphthalenesulfonic acids with mixtures of calcium and zinc bases.
The above-noted preferred neutral salts are prepared by reacting the mono-, di-, and/or poly-alkylated naphthalenesulfonic acid precursors with a metallic compound capable of forming the neutral salts. Many metal bases are known in the art to be suitable for this purpose and include metal oxides, hydroxides, and carbonates. The sulfonic acids are either reacted with a stoichiometric amount of base to form neutral salts, also known as soaps in lubricant additive industry, or with excess base to form basic salts or overbased materials, commonly referred to as detergents. In the latter case, carbon dioxide is often used to convert the base into its carbonate form. While many bases form salts with sulfonic acids, alkali metal and alkaline metal salts are often preferred as lubricant additives. Alkali metal salts employ metal hydroxides, such as sodium hydroxide and potassium hydroxide, as the bases. For alkaline earth metal salts, oxide and hydroxide bases are preferred for magnesium, calcium and barium salts. However, calcium salts derived by the use of calcium carbonate also are known. While for neutral salt formation, contact between organic acid and inorganic base is normally not a problem; for basic (overbased) salt formation, one needs to use promoters that enhance this contact. A wide variety of materials are used for this purpose and include water; ammonium hydroxide; low molecular weight alcohols, such as methanol, isopropanol, and isobutanol; and low molecular weight alkylphenols. To make the neutral salts used in the functional fluids of the present invention, the acid is reacted with a stoichiometric amount of the base and the resulting water and a solvent, if present in the starting sulfonic acid, are removed. The product may be adjusted with diluent oil preferably to provide a metal content between 1.0 to 15 percent. These acids also may be converted to make basic or overbased detergents. While generally the terms basic and overbased imply materials that contain a reserve base, in the context of the present invention this requirement is not necessary. What is necessary is that such materials contain a higher metal content than that in neutral salts. That is, they have a metal ratio greater than 1 (see Chapter 3 on detergents/dispersants by C. C. Colyer and W. C. Gergel, published in xe2x80x9cChemistry and Technology of Lubricants,xe2x80x9d R. Mortier and S. T. Orszulik, VCH Publishers 1992). Metal carbonate and metal borate overbased detergents of the present invention are preferred to have an approximate base number of less than about 500.
The preferred basic metal salts of the mono-, di-, and/or poly-alkylated naphthalenesulfonic acids are represented by the formulae (III), (IV), and (V): 
wherein R1, R2, R3, R4, l, m, n and p are as defined above for formula (I) and M is a metal ion selected from the group consisting of alkali metal, alkaline earth metal, transition metal, Group IVb metal, and Group Vb metal; x is the valence of M and z is from 0.1 to 50.
When basic or overbased metal salts are employed in the functional fluids of the present invention, the same alkali metals, alkaline earth metals, transition metals, Group IVb metals and Group Vb metals preferred for neutral salts also are preferred for these basic metal salts. In some instances, it may be preferred to use mixtures of the same class or different classes of basic metal salts.
The above-noted preferred basic metal salts are prepared by reacting or otherwise combining the mono-, di-, or poly-alkylated naphthalenesulfonic acid precursor with a metallic compound selected from the classes M2(O)x, M(OH)x, or M2(CO3)x. and combinations thereof. Metal carbonate overbasing typically requires the use of carbon dioxide as a reactant. Metal borate overbasing, on the other hand, requires the use of boric acid. Metal sulfate and metal thiosulfate overbased materials are made by reacting the metal carbonate overbased material with sulfur dioxide and subsequent oxidation with oxygen and sulfur. See U.S. Pat. Nos. 5,484,542; 5,064,545; and 4,539,126 for procedures describing the preparation of these salts.
The carbonate-containing basic (overbased) metal salts can be made either from the neutral salt or directly from the alkylnaphthalenesulfonic acids. The first method involves taking a neutral salt, suspending it in an organic solvent, such as toluene, adding a base and blowing the reaction with carbon dioxide. The second method involves first making the neutral salt in situ by reacting the arylsulfonic acid with the metal base, adding excess base and then blowing the reaction with carbon dioxide. The latter method is preferred, since it does not involve isolation of the neutral salt prior to overbasing. The metal borate overbased products can be made either directly from the sulfonic acid, as described in U.S. Pat. No. 6,090,757; or by reacting the carbonate overbased product with a boron source, preferably boric acid. This is described in U.S. Pat. No. 5,484,542. This patent also teaches the methodology to make sulfite detergents by first displacing the CO2 of the carbonate overbased detergents with SO2. The sulfite overbased materials are then converted into sulfate and thiosulfate overbased products via reaction with an oxygen or sulfur source, respectively.
The preferred amine salts of the mono-, di-, and/or poly-alkylated naphthalenesulfonic acids are either ammonium or amine salts as represented by formulae (VI) and (VII): 
wherein R1, R2, R3, R4, l, m, n and p are the same as defined above and R5 is individually a hydrogen atom or a hydrocarbyl group containing from 1 to 25 carbon atoms, and x is from 2 to 5.
The above-noted amine salts are made preferably by reacting or otherwise combining the mono-, di-, and/or poly-alkylated naphthalenesulfonic acid precursors with an amine compound selected from primary, secondary or tertiary amines, as well as ammonia. The preferred amine derivatives are those derived from primary monoamines, such as t-alkylamine (Primene 81R, Rohm and Haas supplier), oleylamine, and tallowalkylamine (Akzo Nobel supplier); secondary amines, such as dicocoalkylamine and ditallowalkylamine (Akzo Nobel supplier); diamines, such as N-coco-1,3-diaminopropane and N-oleyl-1,3-diaminopropane (Akzo Nobel supplier); etheramines, such as isododecyloxypropylamine and N-isodecyloxypropyl-1,3-diaminopropane (supplied by Tomah Products, Inc.), and some of Jeffamine M and Jeffamine D products (Huntsman Corporation supplier); and ethoxylated amines, such as ethoxylated cocoalkylamine and ethoxylated N-tallow-1,3-diaminopropane (Azko Nobel""s Ethomeen C/12 and Ethoduomeen T/13).
The amine salts of the present invention are made by reacting the sulfonic acid or acids with the appropriate amine. Usually, the amine is added to the acid with temperature control because the reaction is exothermic. The temperature of the reaction typically is maintained around 80xc2x0 C. or below to minimize acid reversal to the free alkylate.
The preferred esters of the mono-, di-, and/or poly-alkylated naphthalenesulfonic acids are represented by formula (VIII): 
wherein R1, R2, R3, R4, l, m, n and p are the same as defined above and R6 is a hydrocarbyl group containing from 2 to 18 carbon atoms.
The above-noted esters are preferably made by reacting or otherwise combining the mono-, di-, and/or poly-alkylated naphthalenesulfonic acids precursor with an unsaturated compound, such as acrylic acid, methacrylic acid, and derivatives thereof, styrene, vinyl alcohol and vinyl acetate or a reactive organic compound, such as an aldehyde, ketone, or a cyclic oxide. The sulfonate esters derived from alkyl acrylates, alkyl methacrylates, and olefin epoxides are amongst those that are most preferred. Generally, these compounds are reacted with the alkylnaphthalenesulfonic acids under anhydrous conditions to form the esters of the present invention. Because typically such a reaction is exothermic, temperature control is usually employed.
The amount of the functional fluid base component (a) should be preferably at least about 50% by weight of the total functional fluid composition; more preferably, at least about 75% by weight of the total functional fluid. The preferred amount of the sulfonic acid derivatives should be at least 0.0005% by weight of the total functional fluid. Preferably, it is less than about 25% by weight, more preferably, less than about 10% by weight of the total functional fluid. In a rust preventive coating formulations, the amount can be as high as 25%.
Optionally, the functional fluid composition may include other additives. Optional additives may contain other performance additives known in the art, which include but are not limited to dispersants, detergents, antioxidants, antiwear additives, extreme pressure additives, rust and corrosion inhibitors, copper metal passivators, viscosity index improvers, friction modifiers and the like. The preferred additives in the formulation depend upon the nature of the functional fluid. For combustion engine lubricants and automatic transmission fluids, the preferred additive system primarily comprises dispersant, detergent, antioxidant, antiwear agent, viscosity improver, friction modifier, pour point depressant, foam inhibitor, and rust and corrosion inhibitor. Gear lubricants and hydraulic fluids contain an additive system that includes all other additives listed under engine oils, but is usually free of a dispersant. Industrial hydraulic fluids are also devoid of a friction modifier. Metalworking fluids typically contain detergent, extreme pressure/antiwear agent, antioxidant, corrosion inhibitor/metal deactivator, friction modifier, and foam inhibitor additives. Greases contain a thickener and an additive package comprising an antiwear/extreme pressure additive, an antioxidant, and a corrosion inhibitor. The amount of each additive differs in each of these applications.
The compositions of the present invention may be employed in many applications, including transmission fluids, gear oils, hydraulic fluids, metalworking fluids, and greases. These compositions also are useful in rust-inhibiting formulations, such as rust preventives, where a liquid or semisolid formulation containing an effective amount of at least one rust-inhibiting composition, such as that of the present invention, is applied to metal parts. The evaporation and/or oxidation of the organic components of the formulation results in a coating that protects the metal parts against rust.
In the case of the lubricating oils, an important feature of the invention is the ability of the additive to improve the performance characteristics of a finished lubricating oil, whether derived from a mineral base stock, synthetic base stock, mixtures of these two base stocks, or a grease in which any of the aforementioned base stocks are employed as a vehicle. In general, the mineral base stocks; paraffinic, naphthenic, and mixtures thereof; employed to formulate a lubricating oil or used as the grease vehicle can be of any suitable lubricating viscosity range, as for example, from about 10 cSt to about 2000 cSt at 40xc2x0 C., and preferably from about 25 to about 70 cSt at 100xc2x0 C. These oils may have viscosity indexes ranging from 70 to 120 or higher. Viscosity indexes from about 80 to about 120 are preferred. The average molecular weight of these oils can range from about 250 to about 800. Specific examples of oils of lubricating viscosity are described in U.S. Pat. No. 4,326,972 and European Patent Publication 107,282, both herein incorporated by reference of their disclosures relating to lubricating oils. A basic, brief description of lubricant oils appears in an article by D. V. Brock, xe2x80x9cLubricating Base Oilsxe2x80x9d, Lubrication Engineering, volume 43, pages 184-185, March, 1987. The article is incorporated herein by reference for its disclosures relating to lubricating oils. A description of oils of lubricating viscosity occurs in U.S. Pat. No. 4,582,618 (column 2, line 37 through column 3, line 63 inclusive), herein incorporated by reference for its disclosure to oils of lubricating viscosity.
Where the lubricant is employed as a grease, the lubricating oil is generally used in an amount sufficient to balance the total grease composition, after accounting for the desired quantity of the thickening agent and other additive components included in the grease formulation. A wide variety of materials can be employed as thickening or gelling agents. These can include any of the conventional metal salts or soaps, such as calcium, or lithium stearates or hydroxystearates, which are dispersed in the lubricating vehicle in grease-forming quantities in an amount to impart the desired consistency to the resulting grease composition. Other thickening agents that can be employed in the grease formulation comprise the non-soap thickeners, such as surface-modified clays and silicas, aryl ureas, calcium complexes and similar materials. In general, grease thickeners can be employed which do not melt and dissolve when used at the required temperature within a particular environment; however, in all other respects, any material which is normally employed for thickening or gelling hydrocarbon fluids for forming a grease can be used in preparing the aforementioned improved grease in accordance with the present invention.
In instances where synthetic oils, or synthetic oils employed as the vehicle for the grease are desired in preference to mineral oils, or in preference to mixtures of mineral and synthetic oils, various synthetic oils may be utilized successfully. Typical synthetic oil vehicles include polyisobutylenes, polybutenes, hydrogenated polydecenes, polypropylene glycol, polyethylene glycol, trimethylolpropane esters, neopentyl alcohol and pentaerythritol esters, di(2-ethylhexyl) sebacate, di(2-ethylhexyl) adipate, dibutyl phthalate, fluorocarbons, silicate esters, silanes, esters of phosphorus-containing acids, liquid ureas, ferrocene derivatives, hydrogenated synthetic oils, chain-type polyphenyls, siloxanes and silicones (polysiloxanes), and alkyl-substituted diphenyl ethers typified by a butyl-substituted bis (p-phenoxy phenyl) ether, and phenoxy phenylethers.
It is to be understood that the compositions contemplated herein also can contain other materials. For example, other corrosion inhibitors, extreme pressure agents, viscosity index improvers, co-antioxidants, antiwear agents, and the like can be used. These include, but are not limited to, phenates, sulfonates, succinimides, zinc dialkyl or diaryl dithiophosphates, and the like. These materials do not detract from the value of the compositions of this invention.
The hydraulic fluids of the present invention have particularly advantageous characteristics that make them better than previously commercially available functional hydraulic fluids that incorporated the branched alkylarylsulfonic acids of the prior art. For example, in hydraulic fluids in particular, these characteristics include better rust inhibition and better demulsibility, without adversely affecting the wet AFNOR filtration performance of the finished fluid.
The present invention is further described in detail by means of the following Examples and Comparisons.